Objective: To examine the association between antipsychotic use and venous thromboembolism (VTE) in a Taiwan population.

Method: We conducted a nested case-control study using the National Health Insurance Research Database in Taiwan. A total of 2,162 cases with VTE (defined as pulmonary embolism and infarction [ICD-9-CM-code: 415.1] or deep vein thrombosis [ICD-9-CM-codes: 451.1x, 451.81, or 453.8]) and 12,966 matched controls were identified from 2001 to 2010. Antipsychotic exposure status was measured, and potential confounding factors were adjusted for in the analyses. Conditional logistic regressions were applied to determine the effect of antipsychotic use on VTE.

Results: Current antipsychotic use was associated with an increased risk for VTE (adjusted odds ratio [AOR]=1.52; 95% CI, 1.19–1.93). Among current antipsychotic users, new users had a higher risk of VTE (AOR=3.26; 95% CI, 2.06–5.17), whereas the risk among continuous users was modest but not statistically significant (AOR=1.18; 95% CI, 0.89–1.56).

Conclusions: The results demonstrated an increased risk of VTE among subjects with current antipsychotic use. Antipsychotic drugs should be prescribed with caution and attention to the increased risk of VTE. The underlying mechanisms related to the effect of antipsychotics on VTE development warrant further investigation.